On the map Parque Natural Sierras de Tejeda, Almijara, y Alhama, there are several marked Restricted camping areas within the natural park, typically alongside a recreational area. They tend to be in relatively remote and high lying areas. I can find not much information about them in a web search. Some examples on my map include ZAC el Bacal, ZAC el Robledal, and ZAC la Fábrica de la Luz.
My impression is that those campgrounds are rather primitive and unstaffed, perhaps comparable to campgrounds in National Forests in the United States of America. For (western) Europe, this is quite unusual; most campgrounds in Europe are staffed and commercially operated.
On the web I have found a blog article of a group who have camped in El Robledal, which appears to suggest one needs to apply for a permit with the Consejería de Agricultura Pesca y Medio Ambiente 15 days in advance, but this is not an official source. Searching for El Bacal yields a form from a local authority, but it's not clear to me where it should be sent, nor does it include much information on the site. On openstreetmap it's not even marked as a campsite but as a park. I found a mention of camping at Área Recreativa el Alcázar on the Málaga tourism website, but no details on campground facilities, regulations, or reservations.
Where can I find more information or an overview of such campgrounds? For example, are they open year round or seasonally? What group sizes are allowed? What facilities are available and what do people need to bring themselves? Do I really need to apply three weeks in advance with a paper form (by mail? Email? Fax?) or is there a walk-in option as well (subject to availability), perhaps at a park office or with an on-site ranger?